Project-retract mechanism for a ballpoint writing instrument



C. L. MALM May 18, 1965 PROJECT-RETRACT MECHANISM FOR A BALL-POINTWRITING INSTRUMENT Filed Jan. 31, 196:5'

2 Sheets-Sheet l 60er/s L. Mnl/w BY INVENTOR.

rraQA/Eys.

C. L. MALM May 18, 1965 PROJECT-RETRACT MECHANISM FOR A BALL-POINTWRITING INSTRUMENT 2 Sheets-Sheet 2 Filed Jan. 31, 1963 INVENTOR. Caer/5L. MAIL/14 rroeA/Eys.

United States Patent O poration of Delaware Filed Jan. 31, 1963, Ser.No. 255,325 Claims. (Cl. 1Z0-42.03)

This invention relates to an improved writing instrument and moreparticularly an improved project-retract mechanism for use in a writinginstrument of the ball-point type wherein the ball-point is adjustableinto a projected position for use in writing and into a retractedposition with the ball-point concealed within the pen housing.

The improved project-retract mechanism of the present invention isadapted for use in a ball-point writing instrument of the type embodiedin Patent 2,941,510l issued l une 2l, 1960, wherein an inclinable latchmember is carried within a barrel and cooperates with the barrel to holdthe writing unit of the pen in alternative projected writing positionand retracted carrying position. It is very important that the step ofretraction of the writing unit positively and reliably return thewriting tip into the pen housing, to permit the pen to be carried in ashirt or coat pocket with assurance that the writing tip will not soilclothing or otherwise stain the pocket with ink. If the pen is throwninto a handbag the other contents of the handbag may become stained ormarked up if the tip is not completely retracted. It has been found thatrepeated use of a pen causes dust, dirt `or foreign matter to accumulateand become imbedded in the retract mechanism of prior pens, causing thewriting tip to sometimes stick or jam up on the retract motion. Thepresent invention provides a more positive and dependableretractmechanism eliminating the possibility of having the writing unit stickor jamin an undesired' projecting position.

v If has also been found that dust and dirt sometimes collects on thelatch member after repeated and continued use which causes the latchtovslip out of engagement with the cooperatively shaped barrel causingthe writing unit to be retracted unintentionally. The present inventionprovides a more positive and reliable engagement feature that requires apositive operation to actuate the retract mechanism.

Accordingly, it is a general object of the present invention to providea project-retract mechanism that causes a quick, positive and reliableretraction of the writing tip of the ball-point pen.

Another object of the present invention is the provision of aproject-retract mechanism that more positively locks the writing unit inalternate projected and retracted positions.

Other objects and advantages of this invention will be readily apparentfrom the following description when considered in connection with theappended drawings.

In the drawings:

FIG. 1 is a longitudinal view in section and in elevation showing awriting instrument containing a preferred embodiment of theproject-retract mechanism of the present invention with the writing tipin the projected or writing position.

FIG. 2 is an enlarged longitudinal view in section and in elevationshowing the upper portion of FIG. 1.

FIG. 3 is an enlarged longitudinal view in section and in elevationtaken along plane III-III of FIG. 2.

FIG. 4 is an enlarged longitudinal view in section and in elevationsimilar to FIG. 2 showing the position of the latch immediately afterthe plunger has been depressed to retract the writing unit.

FIG. 5 is a transverse section taken along plane V-V l ef FIG. 2.

ice

FIG. 6 is a transverse section taken along plane VI-VI of FIG. 2.

FIG. 7 is a longitudinal section similar to FIG. 2 showing the positionof the latch in the retracted position.

FIG. 8 is a longitudinal section similar to FIG. 3 taken along planeVIII- VIII of FIG. 7.

FIG. 9 is a longitudinal section showing the position of the latch theinstant it engages the project stop shoulder.

FIG. l0 is a transverse section taken along plane X--X of FIG. 7.

FIG. 11 is a transverse section taken along plane XI-XI of FIG. 9.

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown in FIG. l a Writing instrument 20 which incorporates theproject-retract mechanism 21 of the present invention. The writinginstrument 20 has a lower housing portion 26 which is threadablyconnected to the upper housing portion 27. The writing unit 2S isaxially disposed and axially movable within the lower housing portion 26and extends into the upper housing portion 27. The writing unit 28 has awriting tip 29 at its lower end, a latch seat 30 at its upper end and anintermediate enlarged ink reservoir 31. The writing unit it normallybiased toward a retracted position by a spring 34 which may bear onshoulders 32 within the housing at one end and an enlarged section 33 ofthe writing unit 28 at the other end. Rearward of the writing unit 28and entirely within the upper housing portion 27 is the projectretractmechanism 21 of the present invention. The project-retract mechanism 21functions to hold the writing unit 28 in alternate projected or writingposition and retracted position.

As best seen in FIGS. 2, 3, 4, 7, 8 and 9 the projectretract mechanism21 has a barrel 41 which is positioned axially within the upper housingportion 27 and has an axial latch receiving aperture 42. The latchreceiving aperture 42 has an upper polygonal portion 43 and a lowerportion 44 which may either be cylindrical or polygonal. The lowerportion 44 is cooperatively shaped with the latch 51 to prevent thelatch from rotating during operation but which does permit the latch tobe inclined laterally within the aperture 42. One method ofcooperatively shaping the lower portion of the barrel 41 and the latch51 may be to provide longitudinal grooves 45 in the walls of theaperture 44 parallel to the axis of the aperture 42 adapted to slidinglyreceive outwardly extending guides 53 on the latch 5.1. Latch 51 isurged upwardly by writing unit 28 and spring 34.

The upper polygonal portion 43 of the latch receiving aperture 42 has apair of opposing, laterally spaced side walls 46a and 46b. The sidewalls 46a and 46h are provided with a pair of downwardly facing,longitudinally displaced and oppositely inclined project and retractstop shoulders 47 and 48 respectively. The stop shoulders 47 and 48 areadapted to engage and retain latch 51 in alternate projected andretracted positions. As best seen in FIG. 3 the project stop shoulder 47is inclined and may make an acute angle of between 60 and 70 with theaxis of the aperture 42. An angle of 64 with the axis of the aperture 42is preferred. As best seen in FIG. 2 project stop shoulder 47 is alsoinclined with respect to the, side wall' 46a. Because of thisinclination, project stop shoulder 47 and side wall 46aform an acutedihedral angle. This acuate dihedral angle is normally but may be anyacute angle as will become more apparent as this description progresses.This second inclination or undercut provides a more positive engagementor lock on the latch 51 when in its projected position. By undercuttingthe project stop shoulder 47 the writing unit 28 cannot easily beretracted by simply dropping the pen or susanna bumping it. A positiveaction is needed to retract the writing unit 28.

As best seen in FIG. 8 retract stop shoulder 48 has a'lower guide faceportion 48a and an upper guide face portion 48b terminating in theretract stop shoulder. The lower guide face portion 4&1 is inclined toform an acute angle with respect to the axis of the aperture 42. 'Theacute angle formed by the lower .guide face 48a and the axis of theaperture 42 may be between 5 and 27, preferably being 22. This guideface portion 48a is provided to urge the latch laterally as well aspermit it to move longitudinally during the retract motion. By urgingthe latch laterally .back to the retracted position quickly and in thisfashion, the possibility that the latch will stick or jarn is greatlyreduced if not eliminated. The upper guide faceV portion 48h is inclinedopposite to the project stop shoulder 47 and at a similar angle with theaxis of the aperture 42. This upper guide face 4gb is undercut(similarlyto the project stop sholder) to form an acute dihedral anglewith side wall 4611. The undercut upper guide face 48h provides a morepositive engagement between the retract stop shoulder 48 and latch 51when the writing unit 28 is in the retracted position.

Axially positioned within the latch receiving aperture 42 of the barrel41 is an elongated latch or wobbler 51. The latch or wobbler isinclinably seated on latch seat by means of a cooperatively shaped base52. The cooperatively shaped Vbase 52 is shaped so that the latch 51 isfree to move axially while receiving the upward thrust of the springbiased writing unit 28, and be inclinable laterally within the latchreceiving aperture 42. Rotation of the latch about a longitudinal axisis prevented in any suitable manner, as by the guides 53 and grooves 45(see FIG. 11).

The latch 51 has a pair of opposed upstanding side walls 54a and 54b, apair of opposed upstanding edge walls 55a and S5b and a top 56. The top56 of the latch 51 is provided with a pair of laterally spaced andoppositely inclined surfaces 57a and 57i). Each of these inclinedsurfaces 57a and 57b intersect each of the side walls 54a and 54h toform an upper dihedral angle a as best seen in FIG. 3. This dihedralangle a is less than 90 and corresponds to the acute angle formed by theproject stop shoulder 47 and the upper guide face 48h of the retractstop shoulder 48 with the axis of the aperture 42. This actuate anglemay normally be within the range of 60 to 70 but preferably is 64 tocorrespond to the angle of inclination of the stop shoulders 47 and 48h.The inclined surfaces 57a and 57h each intersect one of the edge Walls55a and 55b to form another acute dihedral angle. This second dihedralangle produces an undercut on the inclined surfaces 57a and 57h whichcorresponds to the undercut on the stop shoulder 47 and upper guide face48b. This second dihedral angle may normally be Within the range of 70-89 but is preferably 74 to correspond to the dihedral angles formed bythe stop shoulder 47 and upper guide face 48h with the side walls 46aand 46b of the barrel 41. The second dihedral angle on the latch 51 iscompensated forthe inclination of the latch 51 between a retractedposition to a projected position. This compensation makes the angle seemdifferent numerically but when the latch is inclined in either theproject or retract position the surfaces 57a and 47 or 57b and 48b mateperfectly to form a plane to plane contact between the latch 51 and thebarrel 41. This plane to plane undercut engagement produces a reliableand more positive locking between the latch 51 and the barrel 41. Y

Separating the kopposite inclined surfaces 57a and Sb on the top 56 ofthe latch 51 is an axially projecting centralsurface 58. This centralsurface 58 is usually hemispherical in form to produce a positiveengagement between the latch 51 and the plunger 61.

Axially positioned within the upper housing portion 27 is a depressibleplunger 61. The plunger 61 hasan upper knob portion 62 which protrudesbeyond the upper housing portion 27 through an axially aligned plungerreceiving aperture 36. Centrally positioned on the plunger 61 is anoutwardly flaring ange 63 which is cooperatively shaped with inwardlyextending shoulders 35 provided at the upper end of the upper housingportion 27 to retain theplunger 61 within the upper housing portion 27.Opposite the knob portion-62 and slidingly entering the latch receivingaperture upper portion 43 is an elongated lower body portion 64. Thelower body portion 64 and the latch receiving aperture upper vportion 43may be cooperatively shaped to prevent rotation of the plunger 61 duringsuccessive depressions. At the lower end of the elongated body portion64 are two laterally spaced oppositely inclined project and retract cams65a and 6517 respectively. These project and retract cams 65a and 65hare inclined laterally, upwardly and outwardly as to continuously urgethe hemispherical tip 58 of the latch toward the periphery of the latchreceiving aperture 42 when the plunger is depressed'into contact withthe tip 58. The plunger 61 is biased outwardly toward an undepressedposition by a spring 69.

The operation of the project-retract mechanism of the present inventionto provide a reliable retraction of the writing unit and to provide amore secure locking of the writing unit in both projected and retractedpositions is as follows: Y

As best seen in FGS. 1, 2 and 3 withthe writing unit 28 in the projectedposition the latch 51 is inclined in the position where the inclinedsurface y57a is yforced against and mates with the project stopshoulders 47 by receiving the upward thrust of the spring biased writingunit 28. As can best be seen in FIG. 2 the undercutting of the projectstop shoulder 47 and the inclined surface 57a on the latch 51 insures apositive locking of the latch 51 in this inclined position therebyassuring the user of the pen that the Writing tip 29 will remain inthe'project or writing position until positive actionis taken to retractit. To retract the writing tip 29 plunger 61 Vis depressed compressingspring 69. The retract cam face 6511 of the plunger 61 engagesa'laterally displaced portion of the hemispherical surface 58 ofthelatch 51 inclining the latch 51 to the left as seen in FIGS. 2 and 4while moving the latch 51 axially. The latch 51 is first moved slightlyaxially until the surfaces 47 and 57a become unmated, then the latch 51is inclined into the position shown in FIG. 4. The plunger 61 is thenreleased .and is forced into the undepressed position by the spring 69.Starting with the latch 51 in the position shown in FIG. 4 the inclinedsurface 57b of the latch 51 slides quickly along the lower guide face48a longitudinally and laterally toward the retract positionand retractstop shoulder 48. When the inclined surface 57b of the latch 51 reachesthe upper guide face 4811 it slides the remaining short distance intothe retracted position shown in FIG. 8. The undercutting of surface 57bon the latch 51 and upper guide face 48b provides a positive locking ofthe writing unit 28 in the retracted position. As best seen in FIG. 8whenthe latch 51 reaches the upper guide face 48h the spring 34 biasingthe writing unit 2S andthe latch 51 toward a retract position is justabout fully released. If any dirt or dust accumulates on the upper guideface 48h the inclined surface 57b of the latch 51 may stick or jam up sothat the retract motion is not completed. Therefore the shorter thedistance the inclined surface 57b of the latch 51 has-to slide along theupper guide face 48]: the more reliable and positive the retractmechanism will be.

To Vproject the writing unit 2% the plunger 61 is depressed compressingspring 69.v The project cam face 65a on theplunger 61 engages alaterally displaced portion of the hemispherical end 58 of the latch 51moving the latch axially as well as inclining the latch 51 toward theright as best seen in FIG. 9. When the latch 51 is moved axially enoughto disengage the undercut surface 57b of the latch 51 `from the upperguide face 48h the latch 51 is inclined into an opposite direction asbest seen in rFIG. 9. Edge wall 55b of the latch 51 then slides downside Wall 46a of the barrel 41 until the inclined surface 57a of thelatch 51 is below the project stop shoulder 47. The plunger 61 is thenreleased and it is returned to the undepressed position by the spring69. The inclined surface 57a of the latch 51 and the project stopshoulder 47 are engaged and the inclined surface 57a slides up along theproject stop shoulder 47 under the upward biasing force of spring 34into the writing position as shown in FIGS. l, 2` and 3. Theundercutting of the inclined surface 57a of the latch 51 and the projectstop shoulder 47 provides a very positive engagement between thesurfaces thereby preventing any accidental actuation of the mechanism21. A positive action on the plunger is needed to disengage the latch 51from the project stop shoulder 47 By providing the dihedrally inclinedsurfaces and shoulders herein described it has been found that themechanism is capable of operating positively and dependably for`hundreds of thousands of cycles. IDust, debris and normal -Wear doesnot deleteriously affect the operation of the mechanism.

Obviously many modifications and variations of the present invention are.possible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

fI claim:

1. A project-retract mechanism for a writing instrument having a barreland a writing unit longitudinallyv movable therein between projected andretracted positions and spring means normally biasing the Writing unittoward retrac-ted position, said writing unit having an upper end and alower Writing tip at the other end, comprising:

a hollow barrel having an axially extending latch receiving apertureprovided with opposing, laterally spaced side walls,

said side walls having a pair of longitudinally displaced and oppositelyinclined project and retract stop shoulders,

the retract stop shoulder presenting a loWe-r guide face portion at asmaller angle to the axis of said aperture and an upper guide faceportion at a greater angle to said axis of said aperture, terminating insaid retract stop shoulder,

said upper guide face portion and said project stop shoulder havingsubstantially the same acute dihedral angles with said side walls;

an elongated floating latch member contained within said barrelrearwardly of said writing unit,

-said latch member being in contact with the upper end of said writingunit, movable with said unit and adapted to receive upward thrust ofsaid spring biased writing unit,

said latch member and said barrel being cooperatively shaped to permitlongitudinal sliding and inclination of the latch in opposite lateraldirections and to restrain axial rotation of the latch,

said latch having a pair of opposed upstanding edge wall surfaces, apair of opposed upstanding side wall surfaces and a top including a pairof separate oppositely inclined laterally spaced surfaces separated by aprojecting central surface approximating a hemispherical form, saidoppositely inclined laterally spaced surfaces adapted to cooperate withsaid laterally spaced stop shoulders -in said barrel to retain saidlatch in alternately inclined positions of said latch to hold saidwriting unit in projected and retracted position,

each of said inclined surfaces intersecting said side wall surfaces toform an upper dihedral angle with one of said side wall surfaces of lessthan 90, and also intersecting said edge walls to form an upper dihedralangle of less than 90 with one of said edge walls; and

`an axially aligned depressible plunger carried by the rear end of saidbarrel,

said plunger having an upper knob portion, an annular centrallypositioned flange adapted to retain said plunger within said barrel andan elongated lower body portion,

said lower body portion having a polygonal cross sec- -tion and a tiphaving laterally spaced oppositely inclined surfaces,

said oppositely inclined surfaces on said plunger slope outwardly,laterally and upwardly away from said axis;

said plunger being depressible into contact with laterally spacedportions of said projecting hemispherical surface of said latch inalternative inclined positions thereof so that each successivedepression of said plunger causes inclination of said latch in adirection opposite to that of the preceding depression and inclinationof said latch.

2. A project-retract mechanism for a writing instrument having a barreland a writing unit longitudinally movable therein between projected andretracted positions and Ispring means normally biasing the writing unittoward retracted position, said writing unit having an upper end and alower writing tip at the other end, comprising:

a hollow barrel having an axially extending latch receiving apertureprovided with opposing, laterally spaced side walls,

said side walls having a pair of longitudinally displaced and oppositelyinclined project `and retract stop shoulders,

the retract stop shoulder presenting a lower guide face portion at asmaller angle to the axis of said aperture and an upper guide faceportion at a greater angle to `said axis of said aperture terminating insaid retract stop shoulder;

an elongated floating latch member contained within said barrelrearwardly of said writing unit,

said latch member being in contact With the upper end of said writingunit, movable with said unit and adapted to receive upward thrust ofsaid spring biased writing unit,

said latch member and said barrel being cooperatively yshaped to permitlongitudinal sliding and inclination of the latch in opposite lateraldirections and to restrain axial rotation of the latch,

said latch having a pair of opposed upstanding edge wall surfaces, apair of opposed upstanding side wall surfaces and a top includ-ing apair of separate oppositely inclined laterally spaced surfaces separatedby a projecting central surface approximating a herni- `sperical form,said oppositely inclined laterally spaced surfaces adapted to cooperatewith said laterally spaced stop shoulders in said barrel to retain saidlatch in alternately inclined positions of said latch to hold saidwriting unit in projected and retracted position,

each of said inclined surfaces intersecting said side wall surfaces toform an upper dihedral angle with one of said side wall surfaces of lessthan and also intersecting said edge walls to form an upper dihedralangle of less than 90 with one of said edge walls; and

an axially aligned depressible plunger carried by the rear end of saidbarrel,

rsaid plunger being depressible into contact with laterally spacedportions of said projecting hemispherical surface of said latch inalternative inclined positions thereof so that each successivedepression of said plunger causes inclination of said latch in adirection opposite to that of the preceding depression and inclinationof said latch.

3. A project-retract mechanism for a writing instrument havin-g a barreland a writing unit longitudinally movable therein between projected andretracted positions and spring means normally biasing the Writing unittoward retracted position, said writing unit having an upper end and alower writing tip at the other end, comprising:

a hollow barrel having an axially extending latch receiving apertureprovided with opposing, laterally spaced side walls,

said side walls having a pair of longitudinally displaced and oppositelyinclined project and retract stop shoulders,

the retract stop shoulder presenting a lower guide face portion at asmaller angle to the axis of said aperture and an upper guide faceportion at a greater angle to said axis of said aperture, terminating insaid retract `stop shoulder;

an elongated floating latch member contained within said barrelrearwardly of said writing unit,

said latch member being in contact with the upper end of said Writingunit, movable with said unit and adapted to receive upward thrust ofsaid spring biased writing unit,

said latch member and said barrel being cooperatively `shaped to permitlongitudinal sliding and inclination of the latch in opposite lateraldirections and to restrain axial rotation of the latch, and said latchmember adapted to engage said laterally spaced stop shoulders of saidbarrel to retain said latch in alternately inclined positions of saidlatchto hold said Writing unit in projected and retracted position;

an axially aligned depressible plunger carried by the rear end ofsaidbarrel,

- said plunger being depressible into contact with laterally retractmechanism for a writing unit, the provision of:

a hollow barrel having an axially extending latch receiving apertureprovided with opposing, laterally spaced side walls,

said side Walls having a pair of longitudinally displaced and oppositelyinclined project and retract stop shoulders,

an elongated floating latch member contained Within said barrel andadapted to engage said longitudinally spaced stop shoulders,

spring means within said barrel for biasing said latch member towardsaid stop shoulder,

said retract stop shoulder presenting a lower guide face portion at asmaller angle to the axis of said aperture and an upper guide faceportion at a greater angle to said axis of said aperture, terminating insaid retract stop shoulder.

5. In a writing instrument ibarrel as stated in claim 4 wherein saidretract stop shoulder upper guide face por- `tion and said project stopshoulder form acute dihedral angles with said side walls.

References Cited by the Examiner UNITED STATES PATENTS 2,941,510 6/60Marcotte 1Z0- 42.03

FORElGN PATENTS 353,997 6/61 Switzerland. 851,510 l0/6() Great Britain.

30 JEROME SCHNALL, Primary Examiner.

LAWRENCE CHARLES, Examiner.

4. IN A WRITING INSTRUMENT BARREL FOR USE WITH A PROJECTRETRACTMECHANISM FOR A WRITING UNIT, THE PROVISION OF: A HOLLOW BARREL HAVINGAN AXIALLY EXTENDING LATCH RERECEIVING APERTURE PROVIDED WITH OPPOSING,LATERALLY SPACED SIDE WALLS, SAID SIDE WALLS HAVING A PAIR OFLONGITUDINALLY DISPLACED AND OPPOSITELY INCLINED PROJECT AND RETRACTSTOP SHOULDERS, AN ELONGATED FLOATING LATCH MEMBER CONTAINED WITHIN SAIDBARREL AND ADAPTED TO ENGAGE SAID LONGITUDINALLY SPACED STOP SHOULDERS,SPRING MEANS WITHIN SAID BARREL FOR BIASING SAID LATCH MEMBER TOWARDSAID STOP SHOULDER, SAID RETRACT STOP SHOULDER PRESENTING A LOW GUIDEFACE PORTION AT A SMALLER ANGLE TO THE AXIS OF SAID APERTURE AND ANUPPER GUIDE FACE PORTION AT A GREATER ANGLE TO SAID AXIS OF SAIDAPERTURE, TERMINATING IN SAID RETRACT STOP SHOULDER.